• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.47-54
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• 2018

In this paper, we describe the thermal characteristics of the output voltages of ethanol gas sensor according to the amount of radiation incident on the infrared sensors located at each focal point of two elliptical waveguides. In order to verify the output characteristics of the gas sensor according to the amount of incident light on the infrared sensor, two combinations of sensor modules were fabricated. Hydrophobic thin film is deposited on one of the reflectors of sensor modules and one of the two infrared sensors was equipped with a hollow disk (10 Ø), and the temperature characteristics of the infrared sensor equipped with the hollow disk (10 Ø) and the infrared sensor without the disk were tested. The temperature was varied from 253 K to 333 K at 10 K intervals based on 298 K. The properties of ethanol gas sensor have been identified with respect to varying temperature for a range of ethanol concentration from 0 ppm to 500 ppm. In the case of an infrared sensor equipped with a hollow disk (10 Ø), the output voltage of the sensor decreased by 0.8 mV and 1 mV, respectively, as the temperature increased. Conversely, the output voltage of the diskless infrared sensor showed an average increase of 67 mV and 57 mV as the temperature increased. The ethanol concentrations estimated on the basis of results show an error of more than 10 % for less than 100 ppm concentration. However, if the ethanol concentration exceeds 100 ppm, the gas concentration can be estimated within the range of ${\pm}10%$.

• Journal of Radiation Protection and Research
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• v.22 no.2
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• pp.111-117
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• 1997

Recently, the conclusion of Comprehensive Test Ban Treaty(CTBT) is globally constructing a network system for nuclear test monitoring. The radionuclide experts of the Conference on Disarmament recommended that the detection of nuclear debris in the atmosphere was an essential factor of nuclear test monitoring and proposed the technical requirements. Based on those requirements, atmospheric radionuclide monitoring system to detect nuclear debris generated from the nuclear explosion test was composed. The system is comprised of high volume air sampler(HVAS), filter paper presser and high purity germanium detector(HPGe). Minimum detectable concentrations(MDCs) of the key nuclides requiring in CTBT monitoring strategies are determined by considering of decay time, counting time and flow rate of the high volume air sampler for the rapid explosion and the optimum measurement condition. The results were selected $10{\pm}$2h, $20{\pm}$2h and $850{\pm}50m^3$/h as parameters, respectively. The relation between the natural air-borne radionuclide concentration of $^{212}Pb$ and MDC were calculated which gave effect in the Compton continuum baseline due to those nuclides in the gamma-ray spectroscopy. These results can be used as an actually tool in the CTBT monitoring strategies.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.1
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• pp.71-84
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• 2017

Radon, which enters the interior environment from soil, rocks, and groundwater, is a radioactive gas that poses a serious risk to humans. Indoor radon concentrations are measured to investigate the risk of radon gas exposure and reliable radon concentration mapping is then performed for further analysis. In this study, we compared the predictive performance of various univariate kriging algorithms, including ordinary kriging and three nonlinear transform-based kriging algorithms (log-normal, multi-Gaussian, and indicator kriging), for mapping radon concentrations with an asymmetric distribution. To compare and analyze the predictive performance, we carried out jackknife-based validation and analyzed the errors according to the differences in the data intervals and sampling densities. From a case study in South Korea, the overall nonlinear transform-based kriging algorithms showed better predictive performance than ordinary kriging. Among the nonlinear transform-based kriging algorithms, log-normal kriging had the best performance, followed by multi-Gaussian kriging. Ordinary kriging was the best for predicting high values within the spatial pattern. The results from this study are expected to be useful in the selection of kriging algorithms for the spatial prediction of data with an asymmetric distribution.

• Journal of Radiation Protection and Research
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• v.31 no.1
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• pp.25-30
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• 2006

To know radon and uranium concentration variations in groundwater with regional difference, groundwaters were sampled at five different Daejeon area. Seventy-five samples were analyzed and forty samples were collected twice at drying and after raining season to know surface water effect. The average radon and uranium concentration of five areas are $270.9{\pm}152.3\;Bq/L,\;43.8{\pm}23.5\;{\mu}g/L$ at Yusung-gu, $112.9{\pm}65.8\;Bq/L,\;0.45{\pm}0.23\;{\mu}g/L$ at Seo-gu, $41.3{\pm}24.0\;Bq/L,\;4.9{\pm}11.3\;{\mu}g/L$ at Dong-gu, $131.8{\pm}99.5\;Bq/L,\;54.3{\pm}127.5\;{\mu}g/L$ at Daeduk-gu and $44.0{\pm}43.0\;Bq/L,\;8.1{\pm}11.6\;{\mu}g/L$ at Jung-gu. The mean concentrations of analyzed samples to know surface water effect were ranged from 0.5 to 640 ${\mu}g/L$ for uranium and from 0.4 to 729 Bq/L for radon. The average concentration of radon and uranium after raining season were lower than those of drying season. The mean contents of radon End Uranium at drying season were $253{\pm}14\;Bq/L,\;63{\pm}12.2\;{\mu}g/L$, and $195{\pm}11\;Bq/L,\;45.4{\pm}11.7\;{\mu}g/L$ after raining season.

• Journal of Radiation Protection and Research
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• v.27 no.3
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• pp.127-146
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• 2002

A method of more realistically, predicting radionuclide concentrations in crop plants varying with time after a nuclear accident was established to estimate 50 years' concentrations of $^{90}Sr$ and $^{137}Cs$ in polished rice seeds and Chinese cabbage for unit dry deposition. After non-growing season accidents, concentrations of both nuclides decreased gradually with time and $^{90}Sr$ concentrations were higher than those of $^{137}Cs$ throughout the whole period. Radionuclide concentrations in the 1 st year after growing season accidents were on the whole higher than those after non-growing season accidents by factors of up to 30 for $^{90}Sr$ and up to 1,000 for $^{137}Cs$. In polished rice seeds, the 50 years-integrated concentration was higher for $^{90}Sr$ than for $^{137}Cs$ after non-growing season accidents, whereas the opposite was true after growing season accidents. In Chinese cabbage. however, it was higher for $^{90}Sr$ than for $^{137}Cs$ after both types of the accident. Generally speaking, the dominant pathway for the integrated concentration after the growing season accident was root uptake for $^{90}Sr$ and direct plant contamination for $^{137}Cs$. The effect of resuspension was negligible. Based on the predicted results. the direct]on of planning countermeasures was suggested for various accident conditions.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.267-276
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• 2015

Several analyses on tritium that is the largest release of gas or liquid radioactive waste from domestic PWR and PHWR NPPs were carried out, such as release comparison, directional frequency of wind and tritium behavior changes in environmental samples. First of all, analysis result showed that tritium released from PHWR was more than ten times as gas and double to three times as liquid in comparison to PWR in 2013. Independent release management in NPP units is needed to precisely control and analyze tritium, since there were 2 units of some NPPs having the same amount of release during analysis. In analysis on frequency of wind direction, average range showed 1.7 to 11.5% by 16-point compass. In case of analysis on sampling points by wind direction, Result showed most of the sampling points are right in places. However, There are some areas needed to examine. In analysis on tritium concentration changes in environmental samples, tritium concentration near NPPs was higher than one far away from NPPs. In case of environmental samples far from PWR, a trace of tritium occur. While, tritium concentration near NPPs was more than or equal to one further from PHWR. In conclusion, tritium occurs considerably in PHWR and is lower than standard in samples. but, it is still detected. Therefore, it is needed to strengthen control in system in NPPs and to consistently monitor tritium in environment.

• Journal of Radiation Protection and Research
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• v.26 no.4
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• pp.441-445
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• 2001

In this work we investigated distribution of the natural and artificial radioactive nuclides and level of the regional background in soil in Busan. For 45 points, the environmental radioactivity concentration of Busan surface soil is $14.38{\sim}57.03\;(mean\;:\;33.95)\;Bq{\cdot}kg^{-1}$ for $^{226}Ra,\;2.41{\sim}86.58\;(mean\;:\;51.08)\;Bq{\cdot}kg^{-1}$ for $^{228}Ra,\;223.64{\sim}1332.30\;(mean\;668.51)\;Bq{\cdot}kg^{-1}$ for $^{40}K$ and $<0.33{\sim}33.37\;(mean:13.74) Bq{\cdot}kg^{-1}$ for $^{137}Cs$. Also, in order to investigate vertical distribution for radioactivity, we examined radioactive concentration with mountain height. But there was no correlation between radiaoactivity distribution and mountain height. The $^{226}Ra/^{228}Ra$ and $^{226}Ra/^{40}K$ concentration ratios were $0.68{\pm}19 %$ and $0.06{\pm}34%$, respectively.

• Journal of Radiation Protection and Research
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• v.15 no.2
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• pp.27-39
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• 1990

Appreciable radiation exposures certainly were occurred in the reactor burn-up, the nuelear fall-out and the surroundings of nuclear installations with radioactive effluents. Therefore, radioactive nuclides is not only potentially hazardous to workers of nuclear power plants and related industrials, but also the wokers who handle radioactive nuclides in biochemical research and nuclear medicine diagnostics. And in the case of occurring the nuclear accidents, the early medical treatment of radiation injury should be necessary but little is established medical procedures to decontaminate the victims of internal contamination of radioactive nuclides in korea. Accordingly, to achieve the basic data for protective roles and medical treatment of radiation injury, the present studies were carrid out to evaluate the decontamination of uranium by the chemical drugs. The results observed were summarized as follows: 1. The combined treatmet group of sodium bicarbonate and saline with uranyl nitrate injection simultaneously and the dithiothreitol group that was administered 30 minutes after uranyl nitrate injection were increased significantly in the change of body weight than uranyl nitrate-only group (P<0.005). 2. All the experimental groups were increased the fluid intake and urine volume on the uranyl nitrate-induced acute renal failure. but the combined treatment group of sodium bicarbonate and saline with uranyl nitrate injection simultaneously and the dithiothreitol group that was administered 30 minutes after uranyl nitrate injection have the higher increment of fluid intake and urine volume (P<0.05). 3. When sodium bicarbonate and saline was treated with uranyl nitrate injection simultaneously. and dithiothreitol was administered 30 minutes after uranyl nitrate injection. there was significantly reduced in BUN concentration (P<0.01). 4. When dithiothreitol was administered 30 minutes after uranyl nitrate injection. there was reduced more significantly on the increment of serum creatinine concentration than that observed in uranyl nitrate-only group(P<0.01). but when the combined treatment of sodium bicarbonate and saline with uranyl nitrate simultaneously, there was still. albeit much less marked. decrease in serum creatinine concentration. 5. The sodium bicarbonate and saline was treated with uranyl nitrate simultaneously and dithiothreitol was administered at 30 minutes after uranyl nitrate were excreted markedly higher urine creatinine concentration than the uranyl nitrate-only group. 6. Uranyl nitrate has been used in experimental animals to produce hydropic degeneration and swelling of proximal tubules, disappearance of microvilli and brush border or necrosis in the kidney and centrilobular necrosis, congestion, and telangiectasia of the liver. When the sodium bicarbonate and saline was treated with uranyl nitrate simultaneously, and dithiothreitol was administered. 30 minutes after uranyl nitrate, there was more marked the protective effect than uranyl nitrate-only group. Finally, if the sodium bicarbonate and saline may administered as quickly as possible each time that some risk for internal contamination, with uranium, and dithiothreitol is administered 30 minutes after uranium contamination, there ameliorates the course of uranyl nitrate-induced acute renal failure.and this effect is assocciated with prevention of uranium (heavy metal)-induced alterations in BUN, serum creatinine, urine creatinine, fluid intake, urine volume and body weight.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.881-889
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• 2020

The objective of this study was to quantitatively measure the changes in radon concentration due to ventilation and air purification plants in the lower and upper floors of a building. This study measured and compared radon concentration in the lower and upper floors of the building by using a radon meter when the room was closed, it was ventilated, and air purification plants were installed at a specific time. One-way ANOVA was conducted to evaluate the effect of treatment (i.e., closure, ventilation, and air purification plants) on radon concentration. The results of this study showed that ventilation and air purification plants significantly decreased radon concentration in the lower and upper floors of the building, but the effect of ventilation and that of air purification plants were not significantly different. Therefore, it will be possible to reduce radon concentration effectively when ventilation and air purification plants are used appropriately.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.3
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• pp.249-256
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• 1999

This study was performed to investigate the changes in flow and composition of saliva in oral cancer patients after radiation therapy. Stimulated whole saliva was collected from 7 patients who were scheduled for over 6,000cGy irradiation (180 - 225cGy fraction $Co^{60}$ therapy, 5 times a week). The flow rate of saliva, and concentration of total protein and IgA were measured before irradiation and 1, 2, 3, 4, 5 days and 1, 2, 3, 4, 6 weeks and 3, 6, 12 months after. The followings are results we obtained: 1. The salivary flow rate before irradiation was $0.8671{\pm}0.4057ml/min$. Significant decrease started 3 days after irradiation and reached a minimum at 4 weeks ($0.2621{\pm}0.2858ml/min$). Afterwards, flow rate started to increase and was on the way to recover at 1 year. 2. The concentration of total protein and IgA before irradiation were $137.2000{\pm}16.9912mg%$ and $3.4200{\pm}1.4114mg%$, respectively. After irradiation, these figures increased significantly and reached a maximum of $366.4000{\pm}174.0583mg%$ and $43.4800{\pm}29.1207mg/ml$, respectively at 6 weeks. Recovery towards normal values started following the end of irradiation and figures at 12 months had lowered to $165.400{\pm}21.1495mg%$ and $4.6200{\pm}2.1580mg/ml$ each. 3. The ratio of IgA to the amount of total protein was 2.5% before irradiation. This began to increase from 1 week following irradiation as the total dose of radiation received was increased (11.9% at 6 weeks). After 1 year from the start of radiation therapy, the ratio was reduced to such level that was before irradiation.